Quadrupolar Response of Plasmonic Photocathode Fabricated by Coating Electrodeposited Ag Nanoparticles with TiO<sub>2</sub>

Photoelectrodes based on plasmon-induced charge separation (PICS) often consist of Au nanoparticles (NPs) supported on an n-type semiconductor electrode and work as photoanodes.Meanwhile, there are fewer studies on plasmonic photocathodes fabricated by coating a plasmonic NP-modified electrode with the semiconductor.In the present study, plasmonic photocathodes in which Ag NPs electrodeposited on an indium tin oxide (ITO) electrode are covered with TiO2 (ITO/Ag/TiO2) were fabricated via a spray pyrolysis method.The photocathode exhibited efficient absorption and photocurrent responses derived from quadrupolar localized surface plasmon resonance (LSPR) mode.Since there are few studies on ITO/Ag/TiO2 photocathode and the quadrupole mode shows a smaller scattering/extinction ratio and longer lifetime than the dipolar mode, the insights obtained in the present study would lead to the design of highly efficient plasmonic photocathodes.